12708 Mercruiser SEAL

start by:a) remove oil pumpb) remove oil pan plate 1. Remove the No. 1, 3, 5 and 7 main bearing caps (1). Remove the crankshaft thrust bearing from the No. 7 main bearing.2. Remove the lower half of the main bearing from the main bearing caps.
If the crankshaft is turned in the wrong direction, the tab on bearing will be pushed between the crankshaft and bearing area in block which can cause damage to the block or crankshaft.
3. Install tool (A) in the oil hole in the crankshaft journal and remove the upper half of the main bearing as the crankshaft is turned and the main bearing is moved out of the cylinder block. Install the main bearings dry when the clearance checks are made. Put clean engine oil on the main bearings for final assembly.
Make sure the upper and lower halves of the main bearings are installed so the bearing tabs fit into the notch in cylinder block and the main bearing caps.
4. Install new lower half of main bearings (2) in the main bearing caps. Use tool (A) and install the upper half of the main bearings in the cylinder block.5. Put clean oil on the thrust bearing and install a new thrust bearing for the No. 7 main bearing. Install the thrust bearing with the identification "BLOCK SIDE" toward the cylinder block and the tabs on the thrust bearings in the machined area in the cylinder block. The tabs will not let the thrust bearing be installed backward. When the bearing clearance is checked and the engine is in a vertical position, such as in the vehicle, the crankshaft will have to be lifted up and held against the upper halves of the main bearings to get a correct measurement with the Plastigage. The Plastigage will not hold the weight of the crankshaft and give a correct indication. If the engine is in a horizontal position, it is not necessary to hold the crankshaft up. Do not turn the crankshaft when the Plastigage is in position to check clearances.6. Check the main bearing clearances with Plastigage (B) as follows: a) Put a piece of Plastigage (B) on the surface of the lower half of the main bearing.
Make sure the part number on the main bearing cap is toward the front of the engine and the number on the main bearing cap is the same as the number on the cylinder block on the left side of each main bearing cap.
Do not turn the crankshaft when Plastigage (B) is in position. b) Install main bearing caps (1) for No. 1, 3, 5 and 7 main bearings. Put clean engine oil on the bolt threads and the face of the washers and install the bolts. Tighten the bolts to a torque of 40 4 N m (30 3 lb.ft.).
Do not use an impact wrench to tighten the bolts the additional 90°.
c) Put a mark on each bolt and main bearing cap, then tighten the bolts 90° more.d) Remove the main bearing caps for No. 1, 3, 5 and 7 main bearings. Remove Plastigage (B) and measure the width of the Plastigage. The main bearing clearance must be 0.076 to 0.165 mm (.0030 to .0065 in.). Maximum permissible clearance with used bearings is 0.25 mm (.010 in.).7. Install main bearing caps (1) and tighten the bolts as in Steps 6b and 6c.8. Remove No. 2, 4 and 6 main bearing caps. Do Steps 2, 3, 4, 6 and 7 for the No. 2, 4 and 6 main bearings.
TYPICAL EXAMPLE9. Check the crankshaft end play with tooling (C). The end play is controlled by the thrust bearings on the No. 7 main bearing. End play with new bearings is 0.064 to 0.368 mm (.0025 to .0145 in.). The maximum permissible end play with used bearings is 0.64 mm (.025 in.).end by:a) install oil pan plateb) install oil pump